Such pressure regulators are preferably used in vehicle heaters driven with liquid fluid, independent of the engine. Such pressure regulators serve as a power supply unit for the dosing pump by which the liquid fuel, gasoline or diesel fuel, is fed to the vehicle heater. Such heating units are very compact arrangements, which because of their low fuel requirement and their compactness are very dissimilar to home heaters. It is necessary in these heating devices that the dosing pump always uniformly feed the fuel for the heating device, independent of the supply pressure, with the dosing pump requiring a constant inlet pressure for better filling of the dosing space.
Pressure regulators of this type are known, in which the inlet connection, provided with a boring, carries a truncated cone shaped extension and in which the adjusting lever has a two part shape, with one part arranged swingably on a base plate and the other part being in the form of an axially adjustable pressure pin which is engaged by the adjusting piece transferring the movement of the diaphragm. On its side facing the inlet connection, the axially adjustable pressure pin has a level sealing element which at an appropriate deflection of the adjusting lever interrupts the flow of the liquid in that it rests on the truncated cone-shaped extension of the inlet connection. However, this known pressure regulator has a number of disadvantages. It should be noted that because of the installation conditions of heating devices for vehicles, such pressure regulators can have only small dimensions. Therefore, the pressure regulators have to be adjusted with extraordinary precision, which in the known arrangements is done by screwing the pressure pin into the rotatingly arranged part, with the pressure pin carrying the seal. However, given the traffic stresses on the vehicle, this adjustment changes easily, so that the pressure regulator becomes useless. By virtue of the design, a leakage in the seal of the inlet connection also easily occurs at greater deflections of the adjusting lever and thus at increased inlet pressure, due to the seal between adjusting lever and inlet connection no longer being in the level position. This is due to the dependency of the level position of the seal on the position of the adjusting lever and therefore, when the pressure area is sloping, the leakage occurs due to uneven surface pressure. In addition, there is the danger of the inlet connection "eroding" into the seal.